Prostate MRI: Not So Difficult Neil M. Rofsky, MD, FACR, FSCBTMR, FISMRM Dallas, TX
What is the biggest barrier to your practice incorporating prostate MRI? 1) I don t know how to read the cases 2) I don t know how to report the cases 3) The endorectal coil 4) Limitations to data processing (DCE, DWI)
How many prostate MRI exams does your practice perform? 1) Zero 2) 2/week 3) 3-5/week 4) 6-10/week 5) > 10/week
Designate a Champion Know your subject Imaging Techniques Clinical Consider 1 wk training at program w/high volume Know the concerns of your referring MDs Urology Radiation Oncology Medical Oncology
The MRI Tool Kit Standard imaging Axial T1W T2W Coronal T2W Dynamic contrast enhanced imaging Axial Diffusion Axial Spectroscopy
Plan the Exam: 45 min slot start with a 1 hr slot Set-up (10 min) ERC insertion Glucagon injection Positioning Plan scan (inc sag T2) Standard imaging (15 min) T1 weighted (4 minutes) T2 weighted (11 minutes) Axial, Coronal Diffusion (5 min) b values 0, 800-1000; DCE imaging (10 min) T1 GRE Facilitated with post-processing
Focus On Key Issues PSA / bx mismatch for staging High PSA, low Gleason, low volume Low PSA, high Gleason, any volume Rising PSA, repeat negative bx Detect a focus for biopsy
Endorectal Coil MRI Advantages Higher spatial resolution for equivalent time Staging advantage Faster imaging, all other parameters constant Disadvantages Can be uncomfortable Requires experience for optimal placement Best with prep (enema) & glucagon Patient and MD pre-conceptions
Interpretation tips Detection PZ is rarely classic (stranding) Strongest evidence w/ multi-paramter + Low signal T2, w/o high signal T1 DCE: Rapid uptake & washout DWI: High signal on high B value, Low on ADC Staging Read with high specificity Better with ERC Better with 3T DWI ADC map
Size Matters Transverse/axial Sosna, et al. Acad Radiol. 2003 Aug; 10(8):846-53 Bulman, et al. Radiology. 2012 Jan;262(1):144-51. Sagittal
Report Find reporting structure for key referents Keep reporting structure consistent Get familiar with PIRADS
Report Technique (brief!) Overall gland morphology Report size & volume Use sagittal view: AP and CC Use axial view: transverse (Even better planimetry, but time consuming) Features of BPH Describe delineation of PZ
Report: Abnormal Foci Describe with degree of suspicion T2, DCE and DWI congruent? CONSISTENT WITH 2 of 3 Very suspicious 1 of 3 Some features suggestive of Depends on how compelling that 1 is
Report- The Suspicious Foci Describe Position Ax: Clock position, CC: gland into 1/3 s Radial: gland into 1/3 s Describe distance in touch with outer margin Distinguish < vs. > 1.2 cm Describe contour with reference to lesion(s) Describe neurovasc triangles Clearly seen Not well delineated Infiltrated by tumor.
Report: Outside the Gland Describe seminal vesicles Symmetry Visualization / atrophy Multi-parametric features Describe LN s using size criteria.. Describe Bones
76 y.o; PSA = 31; 3 prior neg bx rounds 2.5 x 1.6 cm REPORT: An anterior mass is seen with uniform low signal intensity on T2WI s, measuring 2.5 x 1.6cm, demonstrating abnormal contrast features, very suspicious for cancer. It is located at the mid- portion of gland (C-C dimension) from the 11:00 1:00 position (gland viewed from a lithotomy perspective). A biopsy targeted towards this area is expected to have a high positive yield. There is no definite evidence for extra-capsular extension. IMPRESSION: Anterior gland tumor as described above. Consider targeted biopsy.
Establish & Maintain Credibility Under-promise, over-deliver Follow-up on path Communicate Seek 2 nd opinions on difficult cases Stay current with the literature Ours and theirs!
Pt with progression on active surveillance T2WI Diffusion MAP Van As, et al. Eur Urol. 2009 Dec;56(6):981-7 ADC = 628 mm 2 /s. Tumor ADC was a significant predictor of: 1) adverse repeat biopsy findings (p<0.0001; hazard ratio [HR]: 1.3; 95% CI: 1.1-1.6), 2) time to radical treatment (p<0.0001; HR: 1.5; 95% CI: 1.2-1.8)
Conclusions Prostate MRI offers value to pts & MDs Requires a champion Use standard techniques Buy-in w/dialogue